/*
Copyright (c) 2007,2007 Elizeu Nogueira da R. Jr.

All rights reserved.

Redistribution and use in source and binary forms, with or without modification, 
are permitted provided that the following conditions are met:

    * Redistributions of source code must retain the above copyright notice, 
      this list of conditions and the following disclaimer.
    * Redistributions in binary form must reproduce the above copyright notice, 
      this list of conditions and the following disclaimer in the documentation 
      and/or other materials provided with the distribution.
    * Neither the name of the Elizeu Nogueira da R. Jr. nor the names of its 
      contributors may be used to endorse or promote products derived from this 
      software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.


This package is based on HypersonicSQL, originally developed by Thomas Mueller.
and HSQLDB original developed by the HSQL Development Group
*/

package br.com.dreamsource.mobile.jmesql;

import br.com.dreamsource.mobile.jmesql.exceptions.SQLException;
import java.util.Vector;

class TableFilter {
    private Table      tTable;
    private String     sAlias;
    private Index      iIndex;
    private Node       nCurrent;
    private Object     oEmptyData[];
    private Expression eStart, eEnd;
    private Expression eAnd;
    private boolean    bOuterJoin;

    Object	       oCurrentData[];

    TableFilter(Table t, String alias, boolean outerjoin) {
	tTable = t;
	iIndex = null;
	sAlias = alias != null ? alias : t.getName();
	bOuterJoin = outerjoin;
	oEmptyData = tTable.getNewRow();
    }

    String getName() {
	return sAlias;
    }

    Table getTable() {
	return tTable;
    }

    void setCondition(Expression e) throws SQLException {
	int	   type = e.getType();
	Expression e1 = e.getArg();
	Expression e2 = e.getArg2();

	if (type == Expression.AND) {
	    setCondition(e1);
	    setCondition(e2);

	    return;
	}

	int candidate;

	switch (type) {

	case Expression.NOT_EQUAL:

	case Expression.LIKE:    // todo: maybe use index

	case Expression.IN:
	    candidate = 0;

	    break;

	case Expression.EQUAL:
	    candidate = 1;

	    break;

	case Expression.BIGGER:

	case Expression.BIGGER_EQUAL:
	    candidate = 2;

	    break;

	case Expression.SMALLER:

	case Expression.SMALLER_EQUAL:
	    candidate = 3;

	    break;

	default:

	    // not a condition so forget it
	    return;
	}

	if (e1.getFilter() == this) {

	    // ok include this
	} else if (e2.getFilter() == this && candidate != 0) {

	    // swap and try again to allow index usage
	    e.swapCondition();
	    setCondition(e);

	    return;
	} else {

	    // unrelated: don't include
	    return;
	}

	Trace.assert1(e1.getFilter() == this, "setCondition");

	if (!e2.isResolved()) {
	    return;
	}

	if (candidate == 0) {
	    addAndCondition(e);

	    return;
	}

	int   i = e1.getColumnNr();
	Index index = tTable.getIndexForColumn(i);

	if (index == null || (iIndex != index && iIndex != null)) {

	    // no index or already another index is used
	    addAndCondition(e);

	    return;
	}

	iIndex = index;

	if (candidate == 1) {

	    // candidate for both start & end
	    if (eStart != null || eEnd != null) {
		addAndCondition(e);

		return;
	    }

	    eStart = new Expression(e);
	    eEnd = eStart;
	} else if (candidate == 2) {

	    // candidate for start
	    if (eStart != null) {
		addAndCondition(e);

		return;
	    }

	    eStart = new Expression(e);
	} else if (candidate == 3) {

	    // candidate for end
	    if (eEnd != null) {
		addAndCondition(e);

		return;
	    }

	    eEnd = new Expression(e);
	}

	e.setTrue();
    }

    boolean findFirst() throws SQLException {
	if (iIndex == null) {
	    iIndex = tTable.getPrimaryIndex();
	}

	if (eStart == null) {
	    nCurrent = iIndex.first();
	} else {
	    int    type = eStart.getArg().getDataType();
	    Object o = eStart.getArg2().getValue(type);

	    nCurrent = iIndex.findFirst(o, eStart.getType());
	}

	while (nCurrent != null) {
	    oCurrentData = nCurrent.getData();

	    if (!test(eEnd)) {
		break;
	    }

	    if (test(eAnd)) {
		return true;
	    }

	    nCurrent = iIndex.next(nCurrent);
	}

	oCurrentData = oEmptyData;

	if (bOuterJoin) {
	    return true;
	}

	return false;
    }

    boolean next() throws SQLException {
	if (bOuterJoin && nCurrent == null) {
	    return false;
	}

	nCurrent = iIndex.next(nCurrent);

	while (nCurrent != null) {
	    oCurrentData = nCurrent.getData();

	    if (!test(eEnd)) {
		break;
	    }

	    if (test(eAnd)) {
		return true;
	    }

	    nCurrent = iIndex.next(nCurrent);
	}

	oCurrentData = oEmptyData;

	return false;
    }

    private void addAndCondition(Expression e) {
	Expression e2 = new Expression(e);

	if (eAnd == null) {
	    eAnd = e2;
	} else {
	    Expression and = new Expression(Expression.AND, eAnd, e2);

	    eAnd = and;
	}

	e.setTrue();
    }

    private boolean test(Expression e) throws SQLException {
	if (e == null) {
	    return true;
	}

	return e.test();
    }

}
